The present invention relates to an electrical machine, in particular a generator for motor vehicles, according to the general class of the independent claim.
An electrical machine designed as an alternator is made known in DE 198 04 328 A1, in the case of which the generator shaft is supported by a movable bearing in the hub of a housing part. A spring element inserted in the hub exerts a load on the outer ring of the movable bearing with an axial force to achieve a defined rolling motion of the rolling elements in the movable bearing and thereby attain a longer service life of the movable bearing. The design of this bearing arrangement is relatively complex, since a number of components is required to exert an axial load on the roller bearing. In addition, every single generator and its bearing point must be adjusted to a defined initial axial load using a calibration step. Moreover, with a bearing arrangement of this type, only a relatively steep increase in force in the axial direction can be achieved. Due to longitudinal vibrations of the rotor, then, a relatively steep increase in spring force results and the load on the bearing therefore increases steeply. A steep increase in the spring load and the resultant high overall axial force load on the bearing is disadvantageous, since this could result in an overload, which would greatly shorten the service life of the bearing.